E.g. in School we have 5-7 or 8 hours every day (Math, History, Biology, Chemistry, English etc.).

The first hour starts at 8:00 A.M.

But every Thursday we have an hour that stars at 7:10 A.M.

In the table it will look like this (just random picture from the web): enter image description here

In Czech language we call it:

nultá hodina which is something like zero-ish hour

and then 1st, 2nd and 3rd: první, druhá, třetí hodina

How is nultá hodina (the hour that is before the first hour) called in English?

And how do you write it "shortly"? As 0th ? Or somehow else?

  • Wikipedia explains all: en.wikipedia.org/wiki/0th Mar 9, 2013 at 21:17
  • Using the cipher (0) as an interval indicator is rare and confusing. Hour 1 = t=0-1, hour 2 (the second hour) = t = 1-2 etc (ignoring the interval-boundary–naming problem), but hour 0 is poorly defined. You're probably better thinking laterally, and using the column heading 'pref' or 'ung' say. Jan 6 at 13:34

2 Answers 2


You already had the answer: it’s zeroth.

I think you’ll find that -th is a modestly productive suffix in English for indicating ordinals other than first, second, and third. For example, consider the nth element in a series, or the ith and jth indices of (two-dimensional) matrix. You can even find “epsilonth” (εth) if you look hard enough.

But that one’s rare; zeroth is not. The OED defines zeroth as:

Coming next in a series before the one conventionally regarded as the first.

Its first citation is from the 19th century. So the two series work out to be:

  • In words: zeroth, first, second, third, fourth, fifth, . . . three hundred ninety-fifth, . . .

  • In figures: 0th, 1st, 2nd, 3rd, 4th, 5th, . . . 395th, . . .

  • So, how would you call it with the word "hour"? Do people in UK/USA use it in that way? Or do you use some other word for 0th hour in school? I find also this "noughth". What is better to use with hour and school?
    – Derfder
    Mar 9, 2013 at 21:30
  • 1
    At the school my daughter goes to they actually call it "A" (Ay) hour. But I think in other schools they call it "zero hour" and drop the "th".
    – Jim
    Mar 9, 2013 at 21:32
  • @Jim interesting. Now we have "'A' hour", "zero hour", "zeroth hour", "noughth hour" ;-). In Czech there is only one way how to say it "nulta hodina" or just "nulta" if the other person knows what they are talking about. In English it seems to be more-way-ish :D
    – Derfder
    Mar 9, 2013 at 21:35
  • @Jim So A comes before 1? How does that work? And shouldn’t it be the Aᵗʰ hour still?
    – tchrist
    Mar 9, 2013 at 21:39
  • @tchrist- You expect our school systems to be logically consistent?
    – Jim
    Mar 10, 2013 at 2:00

In English, most people would not recognize the term 'zeroth'. Ordinal numbers start at 'first'. Any other starting point is either a neologism or jocular.

For the hour -before- the first hour, well, that just means what you're calling the first hour is mislabeled and should instead be labeled the second hour.

The case you gave is interesting, where it is an exception to the schedule for one day to have an additional hour before the hour labeled 'first'. To call it 'zeroth' hour would be strange (perfectly recognizable and used by any math geek, but there it is). But then what is the hour that comes before that? There is no word for it that is generally recognizable in English so some other locution would be used, like 'early morning hour' or 'special early class' or something relevant to its function.

Consider this century. In English, it is referred to as the twenty-first century, even though it starts with 20. That's because if you count backwards to the start of the Christian time labeling, the first years marking from when Jesus Christ was supposed to be born is called the 'first century' but isn't the years 101-200 but rather 1 through 100. Czech may do it differently, but this is how it is done in English.

  • 1
    I agree that logically speaking there is something which is always first and something that is last. But in our life, for some reason , for example in mathematics and programming arrays usually start indexing with zero and not 1. Another example could by prime meridian. In Czech and other e.g. German de.wikipedia.org/wiki/Nullmeridian the prime meridian (or the zero meridian thefreedictionary.com/Zero+meridian) is called zero|null|nulty because it is on 0 (start). And I am sure that there are a lot of other exaples as well, including yours with centuries or millenias.
    – Derfder
    Mar 17, 2013 at 6:02
  • 1
    Some system start counting with 0, some with 1. Whichever system, the item at the front is always called the 'first'. Words like 'zeroth' are informal or jocular.
    – Mitch
    Mar 17, 2013 at 21:30
  • 2
    'Zeroth' is certainly used seriously in maths, and has been around (though admittedly rare in common parlance) for over 200 years. But I'd certainly avoid it here. Jan 6 at 13:36
  • What the last paragraph of this answer implies is that, even if one ignored everything that was said before and insisted on assigning a number to that hour, the number should be minus one rather than zero. The century that immediately precedes the first century is the first century BC, where BC functions like minus; there is no zeroth century.
    – jsw29
    Jan 6 at 16:48

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